42 BULLETIN 866, U. S. DEPARTMENT OF AGRICULTURE. 
second set on July 24, four weeks after tjie last sprays had been 
applied (Table 13). 
The most actual copper was found on the leaves sprayed with 
Bordeaux containing 1 per cent of copper sulphate (plats 8, 9, and 
10). Calculated per 0.1 per cent of copper sulphate present in the 
sprays, the leaves from plats 4, 5, and 6, sprayed with the two Pick- | 
ering sprays and the barium-water spray, and gathered directly 
after the sprays had been applied, gave the highest results. Of the 
leaves gathered four weeks after spraying, those treated with the Bor- 
deaux sprays (plats 8, 9, and 10) and with the Pickering sprays 
(plats 5 and 6) gave the highest proportional results. The barium- 
water spray and the two sprays made with sal soda did not adhere to 
the leaves for the four- week period as well as the sprays made with 
lime. The percentage of rotten berries found on the two plats 
sprayed with the sal-soda sprays was low, in spite of the relatively 
small amounts of copper adhering to the leaves at the time of analysis. - 
Apparently, therefore, the amount of copper adhering to a leaf is not 
necessarily a criterion of its protection from fungous diseases. 
Injury to Leaves and Fruit. 
No caustic action of any of the sprays was noted in either 1917 or 
1918. 
Summary. 
None of the sprays tested injured the leaves or berries. 
The Pickering (A) and (C) sprays were equally effective in control- 
ling fungous diseases. Pickering (A) and (C) spra}~s prepared with 
0.6 per cent of copper sulphate seemed to give as effective control 
of fungous diseases on cranberries as Bordeaux, 4-3-50, containing 
1 per cent of copper sulphate, although this was not definitely proven. > 
Practically the same percentage of copper was present on the 
cranberry leaves treated with Pickering spray as on those sprayed 
with standard Bordeaux, rosin-fish-oil soap being used with all the 
sprays. 
Additional tests with the Pickering, barium-water, and sal-soda 
sprays are necessary to obtain conclusive results. 
SUGGESTIONS FOR THE PREPARATION OF PICKERING SPRAY ON A 
COMMERCIAL SCALE. 
The following procedure is recommended for the preparation on 
a commercial scale of a Pickering (A) spray containing 0.7 per cent * 
of copper sulphate : 
STOCK SOLUTION OF COPPER SULPHATE (BLUESTONE OR BLUE VITRIOL). 
Suspend 50 pounds of commercial crystalline copper sulphate 
in a gunny sack in 20 or 30 gallons of water in a clean barrel over 
